Continuous development of access technologies gives rise to a situation of reality in which multiple access technologies coexist, for example, a digital subscriber line (DSL) access technology, a fiber access (Fiber-To-The-X, FTTX) technology, a Long Term Evolution (LTE) access technology, and an E1 access technology, and many network devices may support two or more access technologies simultaneously.
Currently, in the industry, multi-link aggregation is implemented mainly by establishing a virtual private network (VPN) tunnel between a user-side access device and a network-side server, that is, cross-network forwarding and aggregation of packets are implemented by using multiple access technologies simultaneously supported by a network device.
However, in an implementation process of the foregoing technologies, a packet is directly transmitted on the VPN tunnel, and the number of packet encapsulation layers and a packet length are increased. Consequently, the packet transmission efficiency in the foregoing technical solution is low, and a VPN solution further requires additional network address resources.